4 MEMORY AND BUS
S1C17F13 TeChniCal Manual
Seiko epson Corporation
4-1
(Rev. 1.0)
Memory and Bus
4
Overview
4.1
This IC supports up to 16M bytes of accessible memory space for both instructions and data.
The features are listed below.
• Embedded Flash memory that supports on-board programming
• Almost all memory and control registers are accessible in 16-bit width and one cycle.
*
1
• Write-protect function to protect system control registers
Figure 4.1.1 shows the memory map.
0xff ffff
Reserved for core I/O area (1K bytes)
(Device size: 32 bits)
0xff ff80
0xff ff7f
Reserved
0x08 3800
0x08 37ff
RAM area 2 (14K bytes)
*
1
(Device size: 32 bits)
0x08 0000
0x07 ffff
Reserved
0x02 8000
0x02 7fff
Flash area (128K bytes)
(Device size: 16 bits)
0x00 8000
0x00 7fff
Reserved
0x00 6000
0x00 5fff
Peripheral circuit area (8K bytes)
(Device size: 16 bits)
0x00 4000
0x00 3fff
Reserved
0x00 1000
0x00 17ff
0x00 17c0
Debug RAM area (64 bytes)
0x00 17bf
RAM area 1 (6K bytes)
(Device size: 32 bits)
0x00 0000
*
1 RAM area 2 is a shared area for the CPU and EPD timing controller, and one wait cycle will be inserted to the
CPU access cycle (two-cycle access) if this area is accessed from both simultaneously.
1.1 Memory Map
Figure 4.
note
: Be sure to avoid data writing operations to the Reserved areas.
Bus Access Cycle
4.2
The CPU uses the system clock for bus access operations. First, “Bus access cycle,” “Device size,” and “Access
size” are defined as follows:
• Bus access cycle: One system clock period = 1 cycle
• Device size:
Bit width of the memory and peripheral circuits that can be accessed in one cycle
• Access size:
Access size designated by the CPU instructions (e.g., ld %rd, [%rb]
→
16-bit data transfer)
Table 4.2.1 lists numbers of bus access cycles by different device size and access size. The peripheral circuits can
be accessed with an 8-bit, 16-bit, or 32-bit instruction.